Soap bars consist of a blend of different chain length fatty acid soaps. Some of the fatty acid soaps (e.g., typically shorter chain length C14, C12 and below as well as some unsaturated soaps, such as oleate) from which the bars are made are soluble (by “soluble” is generally meant it dissolves at greater than 1 wt. % level in water at less than about 40° C.; it should be understood that solubility may refer to single soaps/surfactants or to mixtures/complexes of soaps and/or surfactants which, as a mixture or complex, have solubility within the defined parameters); and some (e.g., C16, C18 and higher chain lengths) are insoluble or substantially insoluble (again insolubility may refer to mixtures or complexes).
A “typical” soap bar consists of mixtures of saponified nut oils (generally producing more lower chain length, soluble fatty acid soaps) and saponified non-nut oils (generally producing more higher chain length, insoluble fatty acid soaps) which will comprise the various chain length fatty acid and various saturated and unsaturated fatty acid soaps. A typical 85/15 bar, for example, is 85% tallow (comprising longer chain soaps generally required for the structuring when bars are extruded) and 15% coconut (containing shorter, more soluble soaps which yield good foam and other attributes). Such 85115 soaps will generally contain about 50-60% soluble actives.
Applicants have now found that, when the level of soluble actives is kept low (e.g., below about 35% by wt. of bar composition, more preferably below 30% by wt., even more preferably below about 25% of final bar being soluble active, active being soap or synthetic surfactant), then the fragrance delivery is enhanced relative to delivery of fragrance from a bar having higher levels of soluble active in the final bar. In one embodiment of the invention, the bar with low levels of soluble active is predominantly a soap bar or bar comprising a mixture of soap and free fatty acid but, as noted, the bar can be any bar where the amount of the soluble surfactant (e.g., soap, synthetic) is kept at a level of below about 35% by wt. of final bar.
There are a number of references which disclose compositions having mixtures of short and long chain, saturated and unsaturated fatty acids possibly mixed with variety of ions to form soaps. No art of which applicants are aware, however, discloses the criticality of maintaining levels of soluble active below certain level (35% of total active) to enhance perfume delivery or a process/method of enhancing such delivery using the specific compositions of the invention.
U.S. Pat. No. 5,387,362 to Tollens et al. discloses compositions containing a tailored mixture of Mg, Na and K ions reacting with lauric acid, select C14-C18 fatty acids as well as oleic acid to generate soap base. A related reference is U.S. Pat. No. 5,540,852 to KeFauver et. al. There is no disclosure in either reference of compositions with perfume and levels of soluble soaps which must be below certain levels; nor a disclosure of a process for enhancing perfume delivery (e.g., enhanced PEF). Indeed, there is no recognition of preparing bars to ensure the level of soluble soap must comprise no higher than 35% of total surfactant.
U.S. Pat. No. 5,262,079 to Kacher et al. discloses partially neutralizing fatty acids to form a network for a framed bar and also contains high levels of anionic surfactant plus nonionic firmness aids. There is no discussion of compositions with perfume and levels of soluble active below certain level or of processes to enhance perfume delivery. That is, there is no direction or suggestion to prepare bars to ensure final level of soluble active is no more than 35% of total actives. The reference also relates to framed bars versus extrusion bars of the subject invention.
U.S. Pat. No. 6,121,216 to Narath et al. discloses a way to improve processing of a syndet bar which incorporates amphoterics as a mildness aid. Processing efficiency is increased by minimizing levels of soap, especially unsaturated soaps. That soluble active must comprise less than 35% of total active and the influence of such low level on perfume enhancement are not disclosed.